An unmanned aerial vehicle (UAV) is an aircraft without a human pilot aboard. A UAV's flight may be controlled either autonomously by onboard computers or by remote control of a pilot on the ground or in another vehicle. A UAV is typically launched and recovered via an automatic system or an external operator on the ground. There are a wide variety of UAV shapes, sizes, configurations, characteristics, etc. UAVs may be used for a growing number of applications, such as police surveillance, firefighting, security work (e.g., surveillance of pipelines), surveillance of farms, commercial purposes, etc.